ON THE PREPARATION OP SODA AND CHLORINE. 41 



of common salt, and 102 grains (9 eq.) of peroxide of iron (a 

 lesser proportion than in the former experiment), mixed them in- 

 timately and introduced them into a glass flask, heated by a 

 spirit-lamp. By means of an aspirator of caoutchouc, I drew a 

 current of air, not previously dried, over the heated mixture, and 

 then successively through water, dry hydrate of lime, and a solu- 

 tion of caustic potash. The latter at the close of the experiment 

 gave with hydrochloric acid no odor of chlorine, but the hy- 

 drate of lime similarly treated evolved abundance of it, and in- 

 deed possessed all the properties of bleaching powder. The pro- 

 duction of chlorine and bleaching powder was therefore in this 

 case accomplished, but the large quantity of peroxide of iron re- 

 maining in the residue rendered this unfit for the further treat- 

 ment required for the manufacture of carbonate of soda. I ac- 

 cordingly sought to reduce to a minimum, the quantity of peroxide 

 of iron to be added to the other ingredients, and found that a 

 mixture of 316 grains (2 eq.) of calcined green vitriol, 234 grains 

 (4 eq.) of common salt, and 312 grains (4 eq.) of peroxide of 

 iron was capable of being calcined under the muffle, at a low red 

 heat without melting, and yielded pure chlorine. On continuing 

 the calcination until no more of this gas was evolved, the residue 

 contained in 100 parts : — 



Peroxide of iron 65.9 



Sulphate of soda 31.1 



Chloride of sodium. 3.0, by difference* 



100.0 



Encouraged by this result, I diminished still further the quan- 

 tity of peroxide of iron used, and the temperature employed 

 during the calcination. 316 grains (2 eq.) of calcined green 

 vitriol, 234 grains (4 eq.) of common salt, and 156 grains 

 (= 2 eq.) of ferric oxide yielded chlorine ; on calcination in the 

 muffle, and left a residue weighing 573 grains, and containing in 

 100 parts : — 



Peroxide of iron 54.0 



Sulphate of soda -, 42.1 



Chloride of sodium 3.9, by difference, 



100.0 



